The \({\ell _1}\) - periodogram [1]} is primarily designed to identify the sparsest set of orbital signals that fit the observed RVs. This sparsity is achieved by simultaneously fitting Keplerian signals on an optimally sampled grid of frequencies to the data, regularized by minimizing the \(\ell _1\)  norm of their amplitudes.
[1]} present the algorithm as a tool to search for a representation of the input signal as a sum of a few sinusoidal components, that is, a representation which is sparse in the frequency domain.
